The present invention relates to a purified cyclic olefin polymer and to applications and production process thereof. More specifically, it relates to a cyclic olefin polymer containing substantially no catalyst residue and to applications and production process thereof.
Cyclic olefin polymers having a bulky cyclic olefin as one of constituent elements are a synthetic resin which is excellent in transparency, heat resistance, chemical resistance, solvent resistance, humidity resistance, dielectric characteristics and various mechanical properties and widely used in various fields.
These cyclic olefin polymers can be mainly classified into addition copolymers, ring-opened polymers and hydrogenated ones thereof according to structure. The addition copolymers are produced by addition copolymerization of a cyclic olefin and an xcex1-olefin in a hydrocarbon solvent in the presence of a catalyst selected from a Ziegler catalyst and a metallocene catalyst. The ring-opened polymers are produced by ring-opening polymerization of a cyclic olefin in a hydrocarbon solvent in the presence of a metathesis catalyst. The hydrogenated polymers are produced by reacting double bonds between carbons contained in an addition copolymer or ring-opened polymer produced from a cyclic olefin containing two or more double bonds between carbons with hydrogen in the presence of a catalyst selected from a Ziegler catalyst and a metallocene catalyst to saturate the double bonds. The heat resistance, weatherability and light resistance of a cyclic olefin polymer can be further improved by saturating the double bonds.
In the production process of a cyclic olefin polymer, the removal of a catalyst metal is an extremely important step to maintain such properties as transparency, weatherability, humidity resistance and heat resistance of a resin. The following methods have been proposed heretofore to remove the catalyst metal:
(1) one comprising the steps of injecting a polymer solution into a large amount of a poor solvent to deposit a copolymer precipitate and washing the precipitate with a poor solvent;
(2) one comprising the steps of washing a polymer solution with water containing an acid to extract and remove the catalyst residue (refer to JP-A 2-24319 and JP-A 6-100668);
(3) one comprising the steps of washing a polymer solution with water containing an alcohol or the like to extract and remove the catalyst residue (refer to JP-A 4-45103 and JP-A 6-228235);
(4) one comprising the steps of adding an oxidizing agent or basic compound to a polymer solution to extract and remove the catalyst residue with a poor solvent (refer to JP-A 7-109310); and
(5) one comprising the steps of adding an alcohol, water and the like to a polymer solution, further adding an adsorbent and a filter aid thereto, and removing the catalyst residue by filtration or centrifugation (refer to JP-A 3-66725, JP-A 4-161421 and JP-A 4-363312).
As for the method (1), the poor solvent must be used at least several more times in quantity than the polymer solution, which is a great burden in terms of equipment and cost when it is carried out on an industrial scale, including the recovery of the poor solvent, and purification efficiency is not so high. As for the methods (2), (3) and (4), a waste solution containing a relatively large amount of a catalyst metal is generated, thereby posing a great problem with the disposal of the waste solution. As for the method (5), although a large amount of a waste solution is not produced, the purification efficiency is not so high unless large amounts of the adsorbent and the filter aid are used, smooth filtration is difficult to carry out, and problems occur with regard to the disposal of the filter aid and the recovery of the polymer. Generally speaking, catalyst components used to produce a cyclic olefin polymer include an organic aluminum compound such as an alkyl aluminum or alkyl aluminoxane, and the amount of the organic aluminum compound is larger by far than other catalyst components. The organic aluminum compound extremely readily reacts with water, alcohol or acid and becomes insoluble in a hydrocarbon solvent used in the polymerization reaction. However, its reaction product generally separates out as a gel containing a large amount of the solvent and, in most cases, looks like a homogeneous reaction solution with naked eyes. Therefore, if the reaction solution is directly filtered, the filter is clogged and smooth filtration is almost impossible. Therefore, an adsorbent and a filter aid must be used in most cases.
It is an object of the present invention to provide a process for producing a cyclic olefin polymer having a small content of a catalyst residue, which generates almost no waste solution containing a large amount of a metal and can remove the catalyst residue efficiently by simple means.
It is another object of the present invention to provide a process for producing a cyclic olefin polymer having a small content of a catalyst residue, which can remove catalysts used for polymerization and/or hydrogenation reaction for producing the cyclic olefin polymer by decomposing the catalysts efficiently and rendering the decomposition products insoluble in a reaction solvent used for the polymerization and/or hydrogenation reaction to precipitate them efficiently.
It is still another object of the present invention to provide a process for producing a cyclic olefin polymer having a small content of a catalyst residue, which generates substantially no colored decomposition product by-produced by the decomposition of the above catalysts or can remove the colored decomposition product by adsorbing it to catalyst decomposition products or embracing it in the catalyst decomposition products even if it is generated.
It is a further object of the present invention to provide a process for producing a cyclic olefin polymer having a small content of a catalyst residue, which can produce the above catalyst decomposition products in the form of not a markedly swollen gel but a solid which can be easily filtered.
It is a still further object of the present invention to provide a process for producing a cyclic olefin polymer having a small content of a catalyst residue, which can nearly completely remove even a stable compound such as tris(acetylacetonate)aluminum which is inevitably by-produced when an acetylacetonate complex and an organic aluminum compound are used.
It is a still further object of the present invention to provide a cyclic olefin polymer having a small content of a catalyst residue.
It is a still further object of the present invention to provide use of the cyclic olefin polymer of the present invention as an optical material.
Other objects and advantages of the present invention will become apparent from the following description.
According to the present invention, firstly, the above objects and advantages of the present invention are attained by a process for producing a cyclic olefin polymer in the presence of a transition metal catalyst component soluble in an organic solvent and an organic aluminum compound as catalysts, the process comprising the steps of adding at least one compound selected from the group consisting of an xcex1-oxyacid and xcex2-oxyacid, which have one hydroxyl group and one carboxyl group in the molecule, and derivatives obtained by substituting hydroxyl groups thereof with alkoxyl groups, to a reaction product to precipitate a compound containing a transition metal and aluminum, and separating the precipitate by filtration.